Tubing squeeze-off apparatus

ABSTRACT

A squeeze-off apparatus and method for at least partially locally interrupting the flow of a fluid in a resilient tube or pipe are described. Tubes may be accessed from a single direction, thereby eliminating the need for significant excavation around a buried tube. Squeeze-off is performed using two pairs of jaws which close in a parallel manner, the closed distance between the jaws being adjustable depending on the wall thickness of the tubing, thereby permitting the tube to remain integral for at least one such crimping and release cycle. Embodiments of the squeeze-off apparatus may be locked in place once the tube is crimped, thereby permitting the flow to be reduced or shut off without continued application of force to the squeeze-off jaws of the apparatus.

FIELD OF THE INVENTION

The present invention relates generally to tubing crimping tools and,more particularly, to a tubing squeeze-off tool requiring access to thetubing from a single direction, for cutting off or at least reducing theflow of fluid flowing in a resilient tube or pipe.

BACKGROUND OF THE INVENTION

Buried, resilient pipes, such as polyethylene (PE) pipes are usedextensively throughout the United States for natural gas transmissionand distribution. Leaks in such pipes must be quickly attended tobecause of the risk of explosion since the fluid is both flammable andunder pressure. With increasing natural gas consumption, pipeline repairhas become increasingly important. Current procedures for repairingburied natural gas pipes require excavations both upstream anddownstream of the damage, and isolation of the damaged section of pipeby stopping the flow of fluid on both sides of the damage. The damagedsection may then be repaired or replaced.

Designation: F 1563-01 of the ASTM International defines “squeeze-off”as a technique used to control the flow of gas through a pipe by thecompressing action of a mechanical, hydraulic or pneumatic device.Additionally, squeeze-off may be used, as recommended by the tool orpipe manufacturer, to reduce the flow of gas to an acceptable rate, andunder certain conditions complete stoppage of flow may be obtained.

Gas Industry Standard, GIS/PL2-7:2006, further requires that squeeze-offshall be limited by a positive mechanical ‘stop’ capable of beinginterchanged or reset for the specified size ranges, and the squeeze-offtool shall be capable of being locked mechanically in the loadedposition when squeeze-off is fully applied

In order to expedite the excavation of pipe access holes or trenches,such holes or trenches are kept relatively small, especially when largedigging equipment is unavailable. Access to the tube or pipe to besqueezed-off or crushed is therefore generally from the top or sidethereof, and it is advantageous to employ squeeze-off tools which may beinstalled and withdrawn by a single operator; that is, tools which arerelatively light and maneuverable, yet are capable of reversiblysqueezing off pipes having diameters as large as 4 in. in which a fluid,such as a pressurized gas or liquid is flowing.

SUMMARY OF THE INVENTION

Embodiments of the present invention overcome the disadvantages andlimitations of the prior art by providing a crushing or squeeze-offapparatus for at least partially interrupting the flow of a fluid in aresilient tube or pipe.

It is another object of embodiments of the present invention to providea squeeze-off apparatus for at least partially interrupting the flow ofa fluid in a resilient tube, and adapted for accessing the tube from asingle direction.

It is yet another object of embodiments of the present invention toprovide a squeeze-off apparatus for at least partially interrupting theflow of a fluid in a resilient tube adapted for accessing the tube froma single direction, and which can be locked in place once the tube iscrimped.

It is another object of embodiments of the present invention to providea squeeze-off apparatus for at least partially interrupting the flow offluid in a resilient tube, wherein the tube remains integral for atleast one crimping and release cycle.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

To achieve the foregoing and other objects, and in accordance with thepurposes of the present invention as embodied and broadly describedherein, the squeeze-off apparatus hereof, includes: a first elongatedbase member having a flat first side and a flat second side; a secondelongated base member having a flat first side and a flat second side,wherein the first side of the first base member is parallel to, spacedapart from and faces the first side of the second base member; a driveblock adapted to slide between the first base member and the second basemember; a first inner jaw member rotatable about a first pivot centrallylocated on the first jaw member, and in the vicinity of one end of thefirst base member and the second base member; a second inner jaw memberrotatable about the first pivot centrally located on the second jawmember and in the vicinity of one end of the first base member and thesecond base member, the first jaw member and the second jaw memberrotating between the first base member and the second base member, eachinner jaw member having a leg portion on each side of the pivot thereoftogether forming a generally C-shaped opening capable of receiving thetubing; at least one pair of actuating bars, one end of each actuatingbar pivotably attached to an end of the first inner jaw member oppositethe leg portion thereof, the opposite end of each actuating bar beingpivotably attached to the drive block; a first squeeze-off jaw rotatablein the vicinity of a first end thereof about a second pivot location onthe leg portion of the first inner jaw member; a second flat squeeze-offjaw rotatable in the vicinity of a first end thereof about a secondpivot location on the leg portion of the second inner jaw member; a pairof first positioning bars, one end of each first positioning barpivotably attached in the vicinity of a second end of the firstsqueeze-off jaw or the second squeeze-off jaw opposite the first endthereof, the second end of each first positioning bar being pivotablyattached to the first base member; a third squeeze-off jaw rotatable inthe vicinity of a first end thereof about the second pivot location onthe leg portion of the first inner jaw member; a fourth squeeze-off jawrotatable in the vicinity of a first end thereof about the second pivotlocation on the leg portion of the second inner jaw member; a pair ofsecond positioning bars, one end of each second positioning barpivotably attached in the vicinity of a second end of the thirdsqueeze-off jaw or the fourth squeeze-off jaw opposite the first endthereof, the second end of each second positioning bar being pivotablyattached to the second base member; and means for moving the drive blockbetween the first base member and the second base member; whereby auniform gap is maintained between the first squeeze-off jaw and thesecond squeeze-off jaw, and between the third squeeze-off jaw and thefourth squeeze-of jaw as the drive block is moved.

In another aspect of the present invention, and in accordance with itsobjects and purposes, the method for squeezing-off a tube having apuncture or break in the wall thereof hereof, includes: providing atubing squeeze-off apparatus having a first pair of parallel-closingsqueeze-off jaws and a second pair of parallel-closing squeeze-off jawsspaced apart from the first pair of squeeze-off jaws; providing a firstsqueeze-off retainer effective for maintaining the tube in asqueezed-off condition, and a second squeeze-off retainer effective formaintaining the tube in a squeezed-off condition; locating thesqueeze-off apparatus such that the first pair of squeeze-off jawsstraddles the tube on one side of the puncture or break of the tube, andthe second pair of squeeze-off jaws straddles the tube on the side ofthe puncture or break opposite from the first pair of squeeze-off jaws;crimping the tube on both sides of the puncture or break bysimultaneously closing the first pair of squeeze-off jaws and the secondpair of squeeze-off jaws; placing the first retainer on the tubealongside the first pair of squeeze-off jaws; placing the secondretainer on the tube alongside the second pair of squeeze-off jaws;opening the first pair of squeeze-off jaws and the second pair ofsqueeze-off jaws; and removing the squeeze-off apparatus from the tube.

Benefits and advantages of embodiments of the present invention include,but are not limited to, providing a squeeze-off tool for at leastpartially interrupting the flow of a fluid in a tube or pipe, whereinthe tool is effective for accessing two diametrically opposed surfacesof the tube or pipe to be squeezed-off or crushed from a singledirection, and which can be locked in place once the tube is crimped.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the present inventionand, together with the description, serve to explain the principles ofthe invention. In the drawings:

FIG. 1A is a schematic representation of the top view of an embodimentof the present tubing squeeze-off apparatus showing the squeeze-off jawsin their open configuration, while FIG. 1B is a schematic representationof the embodiment of the invention shown in FIG. 1A showing thesqueeze-off jaws in a preset crimping configuration.

FIG. 2A is a schematic representation of the top view of the tubingsqueeze-off apparatus illustrated in FIG. 1A hereof, with the top basemember removed, showing the squeeze-off jaws in an open configuration asa result of the drive block being withdrawn with the consequent openingof the inner jaws; FIG. 2B is a schematic representation of aperspective top view of the jaw portion of the squeeze-off apparatusshown in FIG. 2A hereof with the top base member in place, illustratingone of the drive block stopping plates attached thereto; and FIG. 2C isa schematic representation of a perspective bottom view of the jawportion of the squeeze-off apparatus shown in FIG. 2B hereof with thebottom base member in place, illustrating the other of the drive blockstopping plates attached thereto and components of an embodiment of thestopping mechanism.

FIG. 3A is a schematic representation of the top view of the tubingsqueeze-off apparatus illustrated in FIG. 1A hereof, with the top basemember removed, showing the squeeze-off jaws in a preset crimpingcondition as a result of the drive block being pushed forward with theconsequent closing of the inner jaws; and FIG. 3B is a schematicrepresentation of a perspective top view of the jaw portion of thesqueeze-off apparatus shown in FIG. 3A hereof with the top base memberin place, illustrating the drive block stopping plate attached theretoand components of an embodiment of the stopping mechanism.

FIG. 4A is a schematic representation of the top view of the tubingsqueeze-off apparatus illustrated in FIG. 1A hereof, with the top basemember and the squeeze-off jaws removed showing the inner jaws in theirpreset closed configuration as a result of the drive block being movedforward; FIG. 4B is a schematic representation of a perspective top viewof the jaw portion of the tubing squeeze-off apparatus illustrated inFIG. 4A hereof with the top base member having been removed; FIG. 4C isa schematic representation of the side perspective view of the jawportion of the tubing squeeze-off apparatus shown in FIG. 4A hereof,illustrating the rotatable drive block stop rod in the drive block andthe slot in the piston; and FIG. 4D is a schematic representation of thetop view of the tubing squeeze-off apparatus illustrated in FIG. 1Ahereof with the top base and squeeze-off jaws removed showing the innerjaws in their open configuration as a result of the drive block beingmoved to its rearward location.

FIG. 5A is a schematic representation of a top schematic view of acutaway of the piston and cylinder of the tubing squeeze-off apparatusillustrated in FIG. 1A hereof, with the top base member having beenremoved, and showing the return spring; while FIG. 5B is a schematicrepresentation of an exploded view of the piston and cylinder shown inFIG. 5A hereof, further illustrating an embodiment of the handlemounting member attached thereto.

FIG. 6A is a schematic representation of a side view of one inner jaw oftubing squeeze-off apparatus illustrated in FIG. 2B hereof, while FIG.6B is a schematic representation of a perspective side view of the innerjaw of the tubing squeeze-off apparatus illustrated in FIG. 6A hereof,FIGS. 6A and 6B showing how the squeeze-off jaws are preset to chosenspacings when closed, and how the force on the crimped tubing ismaintained by the tubing squeeze-off apparatus when hydraulic pressureis reduced.

FIG. 7 is a schematic representation of a perspective view of thesqueeze-off retainer device of the present invention.

FIG. 8 is a schematic representation of a side view of cooperationbetween the tubing squeeze-off apparatus and a retainer device,illustrating the use of the squeeze-off retainer on one side of thetubing squeeze-off apparatus for maintaining the crimped condition ofthe tube if the tubing squeeze-off apparatus is removed.

DETAILED DESCRIPTION OF THE INVENTION

Briefly, embodiments of the present invention include a crimping orsqueeze-off apparatus or tool for at least partially interrupting theflow of a fluid in a resilient tube or pipe. Tubes may be accessed froma single direction, such as from above or from the side thereof,depending on the direction of excavation, thereby reducing the need forsignificantly excavation under and around the tube. Sufficient exposureof the tube to be squeezed-off or crimped that two diametrically opposedsurfaces are accessible to the present tool, is all that is required.The tube squeeze-off apparatus may be locked in place once the tube iscrimped, thereby permitting the flow to be reduced or shut off withoutcontinued application of force to the apparatus. Squeeze-off isperformed using two pairs of jaws which close in a parallel manner, theclosest distance between the jaws being adjustable depending on the wallthickness of the tubing, thereby permitting the tube to remain integralor intact for at least one such crimping and release cycle.

In what follows, the words, crimping, squeezing-off, crushing andpinching-off, as applied to deformable, resilient tubes or pipes, willbe used interchangeably.

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. In the FIGURES, similar or identical structure will beidentified using identical reference characters. Turning now to FIG. 1A,a schematic representation of the top view of an embodiment, 10, of thepresent squeeze-off apparatus is illustrated, showing upper pair ofsqueeze-off jaws, 12 a, and 12 b, in their open condition, located bypositioning bars, 14 a, and 14 b, pivotably attached at locations, 16 a,and 16 b, respectively, to the jaws at one end, and pivotably attachedat locations, 18 a, and 18 b, to block, 20 a, which is attached to upperbase member, 22 a, at the other end, and by pivot locations, 24 a, and24 b, attached to the legs of inner jaws, 26 a, and 26 b, respectively.Inner jaws 26 a and 26 b are pivoted at pivot location, 28, located inupper base member 22 a, as will be described in more detail hereinbelow.Handle, 30, is shown attached to the end of handle mounting member, 31,disposed at the other end of base members 22 a (and 22 b, shown in FIG.1B hereof) from pivot location 28. A hydraulic piston, not shown in FIG.1A, driven by pressure source, 32, through pressure inlet, 34, in handlemounting member 31, operates inner jaws 26 a and 26 b, as will bedescribed hereinbelow. Jaw closing distances are controlled by driveblock stop rod, 36, which is rotated by knurled knob, 38, as will beexplained in more detail hereinbelow, and are determined by the wallthickness of the resilient tubing to be crimped. Tubing guide, 40 a,mounted to the open end of base member 22 a, assists in holding thetubing to be crimped, and is used for tubing having less than 2 in.outer diameter, there being another guide, 40 b, not shown in FIG. 1A,mounted to the open end of base member 22 b. For 2 in. or larger outerdiameter pipes, the open ends of base members 22 a and 22 b act astubing stops, the rounded portions of guide 40 a, no longer beingrequired.

FIG. 1B is a schematic representation of the bottom view of theembodiment of squeeze-off apparatus 10 shown in FIG. 1A, hereof, withthe lower pair of squeeze-off jaws, 12 c, and 12 d, in a preset crimpingcondition. Lower squeeze-off jaws, 12 c, and 12 d are located bypositioning bars, 14 c, and 14 d, pivotably attached at locations, 16 c,and 16 d, respectively, to the jaws at one end, and pivotably attachedat locations, 18 c, and 18 d, to block, 20 b, which is attached to lowerbase member, 22 b, at the other end, and by pivot locations, 24 a, and24 b, attached to the legs of inner jaws, 26 a, and 26 b, respectively.In addition to providing a more gentle application of squeeze-off forcesto pipes and tubing, the combination of lower squeeze-off jaws 12 c and12 d with upper squeeze-off jaws 12 a and 12 b in squeeze-off apparatus10 permits punctures and smaller breaks in the pipe or tubing which fitbetween the pairs of squeeze-off jaws to be isolated.

FIG. 2A is a schematic representation of the top view of tubing crimpingapparatus 10 illustrated in FIG. 1A hereof, with top base member 22 aremoved, showing squeeze-off jaws 12 a and 12 b in an open configurationas a result of drive block, 42, being withdrawn by piston rod, 44, intohydraulic or pneumatic cylinder, 46, with the consequent opening ofinner jaws 26 a and 26 b. FIG. 2B is a schematic representation of aperspective top view of the jaw portion of the squeeze-off apparatusshown in FIG. 2A hereof with top base member 22 a in place, illustratingdrive block stopping plate, 48 a, attached thereto, with slot, 50 a,therein confining the motion of stop rod 36, and adjustable stop, 52 a,at one end thereof. FIG. 2C is a schematic representation of aperspective bottom view of the jaw portion of the squeeze-off apparatusshown in FIG. 2B hereof with bottom base member 22 b in place, alsoillustrating drive block stopping plate, 48 a, attached thereto, withslot, 50 a, therein confining the motion of stop rod 36, and adjustablestop 52 a at one end thereof. It should be mentioned that since thereare two pairs of tubing squeeze-off jaws, a length of tubing or pipe tobe crimped or squeezed-off, will be squeezed-off at two longitudinallyseparated locations on the tube.

FIG. 3A is a schematic representation of the top view of tubingsqueeze-off apparatus 10 illustrated in FIG. 1A hereof, with the topbase member removed, showing squeeze-off jaws 12 a and 12 b in a presetcrimping configuration as a result of drive block 42 being pushedforward by piston rod 44 with the consequent closing of inner jaws 26 aand 26 b; and FIG. 3B is a schematic representation of a perspective topview of the jaw portion of the squeeze-off apparatus shown in FIG. 3Ahereof with top base member 22 a in place, illustrating drive blockstopping plate 48 a attached thereto and with slot, 50 a, thereinconfining the motion of stop rod 36, resting against adjustable stop 52a at one end thereof, thereby limiting the motion of drive block 42.

FIG. 4A is a schematic representation of the top view of the tubingsqueeze-off apparatus 10 illustrated in FIG. 1A hereof, with the topbase member and the crimping jaws removed showing inner jaws 26 a and 26b in their preset closed configuration as a result of drive block 42being moved forward by piston rod 44. Drive rods, 54 a, and 54 b, arepivoted at one end, 56 a, and 56 b, respectively, at one end in driveblock 42, and at the other end at pivot locations, 58 a, and 58 b,respectively, in inner jaws 26 a and 26 b, respectively. Inner jaws 26 aand 26 b are also pivoted at pivot location 28 located in top basemember 22 a, and bottom base member 22 b, not shown in FIG. 4A. FIG. 4Bis a schematic representation of a perspective top view of the jawportion of tubing squeeze-off apparatus 10 illustrated in FIG. 4A hereofwith top base member and stopping plates 48 a and 48 b having beenremoved, illustrating four drive rods pivotably connected to drive block42, two parallel drive rods for inner jaw member 26 a, pivoted at commonpivot location 58 a, and two parallel rods for inner jaw member 26 b,pivoted at common pivot location 58 b.

FIG. 4C is a schematic representation of the side perspective view ofthe jaw portion of tubing squeeze-off apparatus 10 shown in FIG. 4Ahereof, illustrating rotatable stop rod 36, shown having two flat sides,60, and 62, disposed in drive block 42 and slot, 64, in piston 44, thefunction of which will be described hereinbelow, and three of the fourdrive rods, 54 a-54 c. FIG. 4D is a schematic representation of the topview of tubing crimping apparatus 10 illustrated in FIG. 1A hereof withthe top base and crimping jaws removed showing the inner jaws 26 a and26 b in their open configuration as a result of drive block 42 beingmoved to its rearward location by piston rod 44.

FIG. 5A is a schematic representation of a top schematic view of acutaway of piston 44 and cylinder 46 of tubing crimping apparatus 10illustrated in FIG. 1A hereof, with the top base member having beenremoved, and showing return spring, 66, and retainer gland nut, 68,which is affixed in exit hole, 70, of cylinder 46, having bore, 72,therein, return spring 66 acting against piston head, 74, to returnpiston 44 to its withdrawn condition in bore 72 of cylinder 46 when thepressure from hydraulic source 32 (FIG. 1A) is reduced. Piston head 74having o-ring, 76, is forced downward in bore 72 under pressureintroduced through passage, 78, from hole 34. FIG. 5B is a schematicrepresentation of an exploded view of the components of piston 44 andcylinder 46 shown in FIG. 5A hereof, further illustrating an embodimentof handle mounting member, 31, sealably attached to face, 82, ofcylinder 46 by means of flange, 84, having o-ring, 86, for providing thehydraulic seal to cylinder 46. Hole, 88, in piston rod 44 is adapted toreceive drive block stop rod 36.

FIG. 6A is a schematic representation of a side view of slotted driveblock stopping plate 48 a illustrating slotted piston 44 attached to thedrive block 42, not shown in FIG. 6A, and cylindrical rod 36 having atleast one machined face 60 and 62 passing through the drive block andextending through slot 50 a in stopping plate 48 a and engagingadjustable stop 52 a attached to the forward end of the slot, therebypreventing further forward motion of the drive block if the hydraulicpressure is further increased. Knurled knob 38, not shown in FIG. 6A,rotates either rounded portion, 90, of stop rod 36, or either flatportion 60 or 62 to contact adjustable stop 52 a, thereby presetting theclosed position of crimping jaws 12 a and 12 b. A similar configurationis present for drive block stopping plate 48 b, having adjustable stop,52 b, not shown in FIG. 6 a.

FIG. 6B is a schematic representation of the side view of slotted driveblock stopping plate 48 a, shown in FIG. 6A hereof, illustrating taperedstop, 92, inserted into slot 64 in piston 44, engaging rearward portion,94, of the slot in the stopping plate, thereby preventing reward motionof the drive block with consequent opening of crimping jaws 12 a-12 dwhen the hydraulic or pneumatic pressure is reduced, and it is desiredthat the tubing remain crimped by tubing crimping apparatus 10. Forconvenience lower base member 22 b may be adapted, 96 (FIG. 1B), to holdtapered stop 94.

It should be mentioned that drive block 42 may also be operated by ascrew mechanism, not shown in the FIGURES, as would be known to thosehaving skill in the related art area in the event that hydraulicoperation of tubing crimping apparatus 10 is undesirable orinconvenient.

To achieve uniform crimping of tubing, squeeze-off jaws 12 a-12 d aredesigned to close as pairs 12 a and 12 b, and 12 c and 12 d, in aparallel manner throughout their range of motion, by making the radialdistance from center pivot 28 to upper jaw pivot points 24 a and 24 bequal to the radial distance between base member 22 a pivot points 18 aand 18 b of the upper jaw positioning bars 14 a and 14 b, and the upperjaw pivot points 16 a and 16 b, with the same conditions for lower jaws12 c and 12 d.

FIG. 7 is a schematic representation of a perspective view ofsqueeze-off retainer, 98, device of the present invention. The width ofchannel, 100, is chosen to match the thickness of the crimped orsqueezed-off tubing after being crimped by squeeze-off tool 10. Relief,102, permits some expansion of the ends of the crimped tubing. Handleholder, 104, allows retainer 98 to be hammered onto a crimped portion ofa tube and secures handle, 105, by using mating threaded portions onboth parts, as an example, for removing the retainer when the tube is tobe reopened.

FIG. 8 is a schematic representation illustrating cooperation betweentubing squeeze-off apparatus 10 and squeeze-off retainer device 98,shown in FIG. 7, hereof, wherein retainer 98 is disposed on one side oftubing squeeze-off apparatus 10 for maintaining the crimped condition ofthe tube or pipe, thereby permitting tubing squeeze-off apparatus 10 tobe removed. A second retainer may be used on the other side of tubingsqueeze-off apparatus 10 if additional security is desired, or if atubing puncture is to be repaired.

The foregoing description of the invention has been presented forpurposes of illustration and description and is not intended to beexhaustive or to limit the invention to the precise form disclosed, andobviously many modifications and variations are possible in light of theabove teaching. The embodiments were chosen and described in order tobest explain the principles of the invention and its practicalapplication to thereby enable others skilled in the art to best utilizethe invention in various embodiments and with various modifications asare suited to the particular use contemplated. It is intended that thescope of the invention be defined by the claims appended hereto.

1. A tubing squeeze-off apparatus, comprising in combination: a firstelongated base member having a flat first side and a flat second side; asecond elongated base member having a flat first side and a flat secondside, wherein the first side of said first base member is parallel to,spaced apart from and faces the first side of said second base member; adrive block adapted to slide between said first base member and saidsecond base member; a first inner jaw member rotatable about a firstpivot centrally located on said first jaw member, and in the vicinity ofone end of said first base member and said second base member; a secondinner jaw member rotatable about the first pivot centrally located onsaid second jaw member, said first jaw member and said second jaw memberrotating between said first base member and said second base member,said first jaw member and said second jaw member each having a legportion on each side of the pivot thereof together forming a generallyC-shaped opening capable of receiving said tubing; at least one pair ofactuating bars, one end of each actuating bar pivotably attached to anend of said first inner jaw member on either side thereof and oppositethe leg portion thereof, the opposite end of each actuating bar beingpivotably attached to said drive block; a first squeeze-off jawrotatable in the vicinity of a first end thereof about a second pivotlocation on the leg portion of said first inner jaw member; a secondsqueeze-off jaw rotatable in the vicinity of a first end thereof about asecond pivot location on the leg portion of said second inner jawmember; a pair of first positioning bars, one end of each firstpositioning bar pivotably attached in the vicinity of a second end ofsaid first squeeze-off jaw and a second end of said second squeeze-offjaw opposite the first end thereof, the second end of each firstpositioning bar being pivotably attached to said first base member; athird squeeze-off jaw rotatable in the vicinity of a first end thereofabout a second pivot location on the leg portion of said first inner jawmember; a fourth squeeze-off jaw rotatable in the vicinity of a firstend thereof about a second pivot location on the leg portion of saidsecond inner jaw member; a pair of second positioning bars, one end ofeach second positioning bar pivotably attached in the vicinity of asecond end of said third squeeze-off and said fourth squeeze-off jawopposite the first end thereof, the second end of each secondpositioning bar being pivotably attached to said second base member; andmeans for moving said drive block between said first base member andsaid second base member; whereby a uniform gap is maintained betweensaid first squeeze-off jaw and said second squeeze-off jaw and betweensaid third squeeze-off jaw and said fourth squeeze-off jaw as said driveblock is moved.
 2. The tubing squeeze-off apparatus of claim 1, whereinsaid means for moving said drive block comprises a hydraulic cylinderattached to said first base member and said second base member, a pistonactuated by said cylinder and attached to said drive block, and a sourceof hydraulic pressure.
 3. The tubing squeeze-off apparatus of claim 2,further comprising a coil spring through which said piston passes forreturning said drive block to a position whereby said first squeeze-offjaw and said second squeeze-off jaw are separated, when the hydraulicpressure is reduced.
 4. The tubing squeeze-off apparatus of claim 2,further comprising: a first drive block stopping plate perpendicular toand attached to said first base member and said second base member,having a first slot with a chosen length therein and having a forwardend and a rearward end; a second drive block stopping plateperpendicular to and attached to said first base member and said secondbase member, spaced apart from and facing said first stopping plate, andhaving a second slot with a chosen length therein opposing the firstslot and having a forward end and a rearward end; a cylindrical pinpassing through said drive block and adapted to pass through the firstslot and the second slot, whereby the motion of said drive block islimited by the chosen length of the first slot and the second slot atthe forward end and the rearward end.
 5. The tubing squeeze-offapparatus of claim 4, further comprising adjustable stops at the forwardend of each of the first slot and the second slot for determining theminimum distance between said first squeezed-off jaw and said secondsqueeze-off jaw, and between the third squeeze-off jaw and the fourthsqueeze-off jaw.
 6. The tubing squeeze-off apparatus of claim 5, whereinsaid pin has at least one flat longitudinal surface such that the motionof said drive block is limited in the forward direction by the at leastone flat surface and said stops.
 7. The tubing squeeze-off apparatus ofclaim 4, wherein said piston passes between said first stopping plateand said second stopping plate, and has a slot therein in the region ofthe first slot and the second slot, said tubing squeeze-off apparatusfurther comprising a tapered pin adapted to be inserted into the slotthrough either the first slot or the second slot and through the otherslot, respectively, wherein said drive block is prevented from rearwardmotion when the hydraulic pressure is released.
 8. The tubingsqueeze-off apparatus of claim 1, further comprising a first curvedinsert having a chosen diameter and attached to the end of said firstbase member containing the first pivot, and a second curved inserthaving a diameter equal to that of the chosen diameter and attached tothe end of said second base member containing the first pivot, saidfirst insert and said second insert adapted for receiving the tubing tobe crimped.
 9. The tubing squeeze-off apparatus of claim 1, furthercomprising a first pivot block attached to the second side of said firstbase member, wherein the second end of each first positioning bar ispivotably attached to said first pivot block; and a second pivot blockattached to the second side of said second base member, wherein thesecond end of each second positioning bar is pivotably attached to saidsecond pivot block.
 10. The tubing squeeze-off apparatus of claim 1,wherein said tubing comprises resilient plastic tubing.
 11. The tubingsqueeze-off apparatus of claim 10, wherein said plastic tubing comprisespolyethylene tubing.
 12. The tubing squeeze-off apparatus of claim 2,further comprising an elongated handle attached to said cylinder at theend thereof opposite said piston.
 13. The tubing squeeze-off apparatusof claim 1, further comprising at least one squeeze-off retainer formaintaining said tubing in a squeezed-off condition.
 14. The tubingsqueeze-off apparatus of claim 1, wherein the distance from the firstpivot to the second pivot is equal to the distance between the pivotableattachment of each of said first positioning bars to said first basemember and the pivotable attachment of each of said first positioningbars in the vicinity of the second end of said first squeeze-off jaw andsaid second squeeze-off jaw, and equal to the distance between thepivotable attachment of each of said second positioning bars to saidsecond base member and the pivotable attachment of each of said secondpositioning bars in the vicinity of the second end of said thirdsqueeze-off jaw and said fourth squeeze-off jaw.
 15. A method forsqueezing-off tubing having a puncture or break in the wall thereof,comprising: providing a tubing squeeze-off apparatus having a first pairof squeeze-off jaws and a second pair of squeeze-off jaws spaced apartfrom the first pair of squeeze-off jaws; providing a first squeeze-offretainer effective for maintaining the tubing in a squeezed-offcondition, and a second squeeze-off retainer effective for maintainingthe tubing in a squeezed-off condition; locating the squeeze-offapparatus such that the first pair of squeeze-off jaws straddles thetubing on one side of the puncture or break of the tubing, and thesecond pair of squeeze-off jaws straddles the tube on the side of thepuncture or break opposite from the first pair of squeeze-off jaws;crimping the tubing on both sides of the puncture or break bysimultaneously closing the first pair of squeeze-off jaws and the secondpair of squeeze-off jaws; placing the first retainer on the tubingalongside the first pair of squeeze-off jaws; placing the secondretainer on the tubing alongside the second pair of squeeze-off jaws;opening the first pair of squeeze-off jaws and the second pair ofsqueeze-off jaws; and removing the squeeze-off apparatus from thetubing.
 16. The method of claim 15, wherein the tubing comprisesresilient plastic tubing.
 17. The method of claim 16, wherein theplastic tubing comprises polyethylene tubing.